This disclosure relates generally to neutron-gamma density (NGD) well logging and, more particularly, to techniques for obtaining an accurate NGD measurement in certain formations using a correction factor based on elemental spectroscopy.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of any kind.
Techniques have been developed to generate gamma-rays for a formation density measurement without radioisotopic gamma-ray sources. One such technique is referred to as a neutron-gamma density (NGD) measurement. An NGD measurement involves emitting neutrons into the formation using a neutron source, such as a neutron generator. Some of these neutrons may inelastically scatter off certain elements in the formation, generating inelastic gamma-rays that are detected by a gamma-ray detector in the tool that may enable a formation density determination. Although an NGD measurement based on these gamma-rays may be accurate in some formations, the NGD measurement may be less accurate in other formations, depending on the formation composition.